Blueberry flowers have a bell shape and grow in bunches. Pollen is heavy and sticky, and can't easily be blown around by the wind. Also, any pollen falling from a flower is unlikely to land inside another bell.
Many types of blueberry are self-sterile: they can not be pollinated by other flowers of the same variety, and must instead be cross-pollinated with another type of blueberry.
Plant three or more types of blueberries in a patch, and have bees pollinate the blueberry plant flowers.
Native bumblebees and southeastern blueberry bees are good natural blueberry pollinators. Honeybees also are effective, and are often used in commercial blueberry farms.
Native bee populations have been dwindling for decades. To pollinate blueberries on even a small patch, you may need to introduce honeybees. In addition, badly pruned and nurtured blueberries might set only 10% to 20% of their fruit. Take the time to care for your patch properly, and it can set up to 100% of its blossoms.